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leds.py

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+#!/usr/bin/env python
+
+#
+# based on code from lrvick and LiquidCrystal
+# lrvic - https://github.com/lrvick/raspi-hd44780/blob/master/hd44780.py
+# LiquidCrystal - https://github.com/arduino/Arduino/blob/master/libraries/LiquidCrystal/LiquidCrystal.cpp
+#
+
+from time import sleep
+
+class Adafruit_CharLCD:
+
+    # commands
+    LCD_CLEARDISPLAY 		= 0x01
+    LCD_RETURNHOME 		    = 0x02
+    LCD_ENTRYMODESET 		= 0x04
+    LCD_DISPLAYCONTROL 		= 0x08
+    LCD_CURSORSHIFT 		= 0x10
+    LCD_FUNCTIONSET 		= 0x20
+    LCD_SETCGRAMADDR 		= 0x40
+    LCD_SETDDRAMADDR 		= 0x80
+
+    # flags for display entry mode
+    LCD_ENTRYRIGHT 		= 0x00
+    LCD_ENTRYLEFT 		= 0x02
+    LCD_ENTRYSHIFTINCREMENT 	= 0x01
+    LCD_ENTRYSHIFTDECREMENT 	= 0x00
+
+    # flags for display on/off control
+    LCD_DISPLAYON 		= 0x04
+    LCD_DISPLAYOFF 		= 0x00
+    LCD_CURSORON 		= 0x02
+    LCD_CURSOROFF 		= 0x00
+    LCD_BLINKON 		= 0x01
+    LCD_BLINKOFF 		= 0x00
+
+    # flags for display/cursor shift
+    LCD_DISPLAYMOVE 		= 0x08
+    LCD_CURSORMOVE 		= 0x00
+
+    # flags for display/cursor shift
+    LCD_DISPLAYMOVE 		= 0x08
+    LCD_CURSORMOVE 		= 0x00
+    LCD_MOVERIGHT 		= 0x04
+    LCD_MOVELEFT 		= 0x00
+
+    # flags for function set
+    LCD_8BITMODE 		= 0x10
+    LCD_4BITMODE 		= 0x00
+    LCD_2LINE 			= 0x08
+    LCD_1LINE 			= 0x00
+    LCD_5x10DOTS 		= 0x04
+    LCD_5x8DOTS 		= 0x00
+
+
+
+    def __init__(self, pin_rs=24, pin_e=23, pins_db=[17, 18, 27, 22], GPIO = None):
+	# Emulate the old behavior of using RPi.GPIO if we haven't been given
+	# an explicit GPIO interface to use
+	if not GPIO:
+	    import RPi.GPIO as GPIO
+   	self.GPIO = GPIO
+        self.pin_rs = pin_rs
+        self.pin_e = pin_e
+        self.pins_db = pins_db
+
+        self.GPIO.setwarnings(False)
+        self.GPIO.setmode(GPIO.BCM)
+        self.GPIO.setup(self.pin_e, GPIO.OUT)
+        self.GPIO.setup(self.pin_rs, GPIO.OUT)
+
+        for pin in self.pins_db:
+            self.GPIO.setup(pin, GPIO.OUT)
+
+	self.write4bits(0x33) # initialization
+	self.write4bits(0x32) # initialization
+	self.write4bits(0x28) # 2 line 5x7 matrix
+	self.write4bits(0x0C) # turn cursor off 0x0E to enable cursor
+	self.write4bits(0x06) # shift cursor right
+
+	self.displaycontrol = self.LCD_DISPLAYON | self.LCD_CURSOROFF | self.LCD_BLINKOFF
+
+	self.displayfunction = self.LCD_4BITMODE | self.LCD_1LINE | self.LCD_5x8DOTS
+	self.displayfunction |= self.LCD_2LINE
+
+	""" Initialize to default text direction (for romance languages) """
+	self.displaymode =  self.LCD_ENTRYLEFT | self.LCD_ENTRYSHIFTDECREMENT
+	self.write4bits(self.LCD_ENTRYMODESET | self.displaymode) #  set the entry mode
+
+        self.clear()
+
+
+    def begin(self, cols, lines):
+
+	if (lines > 1):
+		self.numlines = lines
+    		self.displayfunction |= self.LCD_2LINE
+		self.currline = 0
+
+
+    def home(self):
+
+	self.write4bits(self.LCD_RETURNHOME) # set cursor position to zero
+	self.delayMicroseconds(3000) # this command takes a long time!
+	
+
+    def clear(self):
+
+	self.write4bits(self.LCD_CLEARDISPLAY) # command to clear display
+	self.delayMicroseconds(3000)	# 3000 microsecond sleep, clearing the display takes a long time
+
+
+    def setCursor(self, col, row):
+
+	self.row_offsets = [ 0x00, 0x40, 0x14, 0x54 ]
+
+	if ( row > self.numlines ): 
+		row = self.numlines - 1 # we count rows starting w/0
+
+	self.write4bits(self.LCD_SETDDRAMADDR | (col + self.row_offsets[row]))
+
+
+    def noDisplay(self): 
+	""" Turn the display off (quickly) """
+
+	self.displaycontrol &= ~self.LCD_DISPLAYON
+	self.write4bits(self.LCD_DISPLAYCONTROL | self.displaycontrol)
+
+
+    def display(self):
+	""" Turn the display on (quickly) """
+
+	self.displaycontrol |= self.LCD_DISPLAYON
+	self.write4bits(self.LCD_DISPLAYCONTROL | self.displaycontrol)
+
+
+    def noCursor(self):
+	""" Turns the underline cursor on/off """
+
+	self.displaycontrol &= ~self.LCD_CURSORON
+	self.write4bits(self.LCD_DISPLAYCONTROL | self.displaycontrol)
+
+
+    def cursor(self):
+	""" Cursor On """
+
+	self.displaycontrol |= self.LCD_CURSORON
+	self.write4bits(self.LCD_DISPLAYCONTROL | self.displaycontrol)
+
+
+    def noBlink(self):
+	""" Turn on and off the blinking cursor """
+
+	self.displaycontrol &= ~self.LCD_BLINKON
+	self.write4bits(self.LCD_DISPLAYCONTROL | self.displaycontrol)
+
+
+    def noBlink(self):
+	""" Turn on and off the blinking cursor """
+
+	self.displaycontrol &= ~self.LCD_BLINKON
+	self.write4bits(self.LCD_DISPLAYCONTROL | self.displaycontrol)
+
+
+    def DisplayLeft(self):
+	""" These commands scroll the display without changing the RAM """
+
+	self.write4bits(self.LCD_CURSORSHIFT | self.LCD_DISPLAYMOVE | self.LCD_MOVELEFT)
+
+
+    def scrollDisplayRight(self):
+	""" These commands scroll the display without changing the RAM """
+
+	self.write4bits(self.LCD_CURSORSHIFT | self.LCD_DISPLAYMOVE | self.LCD_MOVERIGHT);
+
+
+    def leftToRight(self):
+	""" This is for text that flows Left to Right """
+
+	self.displaymode |= self.LCD_ENTRYLEFT
+	self.write4bits(self.LCD_ENTRYMODESET | self.displaymode);
+
+
+    def rightToLeft(self):
+	""" This is for text that flows Right to Left """
+	self.displaymode &= ~self.LCD_ENTRYLEFT
+	self.write4bits(self.LCD_ENTRYMODESET | self.displaymode)
+
+
+    def autoscroll(self):
+	""" This will 'right justify' text from the cursor """
+
+	self.displaymode |= self.LCD_ENTRYSHIFTINCREMENT
+	self.write4bits(self.LCD_ENTRYMODESET | self.displaymode)
+
+
+    def noAutoscroll(self): 
+	""" This will 'left justify' text from the cursor """
+
+	self.displaymode &= ~self.LCD_ENTRYSHIFTINCREMENT
+	self.write4bits(self.LCD_ENTRYMODESET | self.displaymode)
+
+
+    def write4bits(self, bits, char_mode=False):
+        """ Send command to LCD """
+
+	self.delayMicroseconds(1000) # 1000 microsecond sleep
+
+        bits=bin(bits)[2:].zfill(8)
+
+        self.GPIO.output(self.pin_rs, char_mode)
+
+        for pin in self.pins_db:
+            self.GPIO.output(pin, False)
+
+        for i in range(4):
+            if bits[i] == "1":
+                self.GPIO.output(self.pins_db[::-1][i], True)
+
+	self.pulseEnable()
+
+        for pin in self.pins_db:
+            self.GPIO.output(pin, False)
+
+        for i in range(4,8):
+            if bits[i] == "1":
+                self.GPIO.output(self.pins_db[::-1][i-4], True)
+
+	self.pulseEnable()
+
+
+    def delayMicroseconds(self, microseconds):
+	seconds = microseconds / float(1000000)	# divide microseconds by 1 million for seconds
+	sleep(seconds)
+
+
+    def pulseEnable(self):
+	self.GPIO.output(self.pin_e, False)
+	self.delayMicroseconds(1)		# 1 microsecond pause - enable pulse must be > 450ns 
+	self.GPIO.output(self.pin_e, True)
+	self.delayMicroseconds(1)		# 1 microsecond pause - enable pulse must be > 450ns 
+	self.GPIO.output(self.pin_e, False)
+	self.delayMicroseconds(1)		# commands need > 37us to settle
+
+
+    def message(self, text):
+        """ Send string to LCD. Newline wraps to second line"""
+
+        for char in text:
+            if char == '\n':
+                self.write4bits(0xC0) # next line
+            else:
+                self.write4bits(ord(char),True)
+
+def loop():
+	lcd = Adafruit_CharLCD()
+	while True:
+                print("loop")
+		lcd.clear()
+		lcd.message(" LCD 1602 Test \n123456789ABCDEF")
+                sleep(2)
+
+if __name__ == '__main__':
+	loop()